Samples of venous blood were taken on Monday after a free weekend and again on Friday from 38 male and 1 female spray painters and compared with the blood samples from 36 male and 3 female referents.

The elution rate of each DNA sample was standardized by dividing it by the elution rate obtained from simultaneously sampled untreated Chinese hamster V79 cells.

Results The spray painters showed a significantly (P<0.001) higher mean level of strand breaks and alkali-labile sites in the Friday samples [2.05 (SE 0.17) ] compared with the Monday samples [1.38 (SE 0.07) ]. The Monday results of the spray painters were not distinguishable from the referents'[1.41 (SE 0.10) ]. The increase in DNA damage was numerically higher, but only weakly significant (use of masks, P<0.05) or nonsignificant (use of spray booths), when fewer safety provisions were taken.

Conclusions A significant increase in DNA strand breaks and alkali-labile sites was found in spray painters after a week's work.

However, DNA damage seems to be reversible.

The use of modern safety equipment seems to affect DNA damage only marginally. (...)